(FORTUNE Small Business) – THESE DAYS, MOST FOLKS WHO play an ax take for granted their capos, the clamps that change the instrument's key by shortening its strings. But it wasn't always so: Back in the '70s, capos were cumbersome and time-consuming to put on and adjust, leading to embarrassing dead spots during gigs. Worse, they often caused the instrument to slip out of tune.

Good thing Rick Shubb wasn't satisfied with the status quo. In 1976, annoyed by the way his banjo playing would suffer whenever he used a capo, Shubb started toying with designs for a solid-metal version that would clip on quickly and precisely. Within a few years Shubb and partner Dave Coontz had created a capo with a rubber bar of just the right resilience and density to mimic human fingers, along with a lever that would clip it perfectly over the neck. "I still remember the exact moment I tested one and thought, 'This is it!' " Shubb says. "Not only did I know we had it, but I knew this was my future."

Today the Shubb capo can be found on the guitars of everyone from U2 to Bruce Springsteen, and the company's profit has grown about 10% a year for a quarter-century. Shubb since has added numerous other products, including slides, guitar stands, and software for musicians, and in 2006 its capos landed top billing in Acoustic Guitar magazine's Player's Choice awards. Sweet music indeed.